Machines, such as skid steer loaders, multi-terrain loaders, backhoe loaders, agricultural tractors, track-type tractors, articulated trucks, wheel loaders, off-road vehicles, dump trucks, and other types of construction, mining, and agricultural machinery are used for a variety of tasks requiring operator control. Typically, an operator controls these machines while seated in a seat located on the machine for extended periods of time. However, these machines often vibrate during operation, which may cause the operator may fatigue quickly reducing the effectiveness of the operator and the time the operator is able to actively operate the machine.
Consequently, suspensions have been developed to reduce the vibrations passed from the operating machine to the seat of the operator. For example, U.S. Pat. No. 5,251,864 illustrates a scissor suspension that uses rollers to provide low frictional movement of the suspension in response to the vibration of a machine. Roller-type scissor suspensions also permit dampers to be installed to provide fore-aft dampening.
However, a roller may only have one point of contact while moving in a track. Consequently, roller-type scissor suspensions are loosely assembled. A loosely assembled suspension permits specific parts to receive jarring impacts during machine operation. Thus, roller-type scissor suspensions suffer from excessive wear and premature failure.
The inherent looseness of roller-type scissor suspensions may prevent the scissor suspension from adequately reducing the vibrations transmitted from the machine to the seat. Additionally, roller-type scissor suspensions are susceptible to dirt and debris building up in the tracks that inhibit proper movement of the rollers and promote wear and premature failure of the roller-type scissor suspension.
Other scissor suspensions include linkage-type suspensions that permit a strong close-fitting scissor suspension without the looseness associated with roller-type scissor suspensions. Additionally, because of the typically close-fitting assembly of linkage-type scissor suspensions, linkage-type scissor suspensions have better wear patterns and longer service life than roller-type scissor suspensions.
However, linkage-type scissor suspensions may suffer from excessive friction and stiffness, which may prevent linkage-type scissor suspensions from properly moving to dampen the vibrations and shocks of machine use and travel. Additionally, linkage-type scissor suspensions do not support integrated fore-aft or lateral motion dampening.
Typically, these roller-type and linkage-type scissor suspensions are used to help isolate a seat of a machine from the vibrations of the machine, which provides a more comfortable working environment to machine operators. In recent years, more and more equipment has been connected and attached to the seat, significantly increasing the weight that a scissor suspension is required to support. However, these roller-type and linkage-type scissor suspensions may not be robust enough to support this additional weight and effectively dampen the vibrations of the machine. Additionally, when these roller-type and linkage-type scissor suspensions are used, they suffer from accelerated wear and premature failure resulting from this increased weight.
The present invention is directed to overcome one or more of the problems as set forth above.